Photodetector, driving method of photodetector, and distance measuring device

ABSTRACT

A photodetector of the present disclosure includes multiple pixels including a light receiving element, and a sampling circuit that is provided corresponding to the multiple pixels, and samples light reception data output from the pixel on the basis of multiple clock signals having different phases, in synchronization with input of a trigger signal. The sampling circuit switches the phase of the clock signal every time a trigger signal is input. Additionally, a distance measuring device of the present disclosure includes a light source that irradiates an object to be measured with light and a photodetector that detects light reflected by the object to be measured. As the photodetector, a photodetector having the above configuration is used.

TECHNICAL FIELD

The present disclosure relates to a photodetector, a driving method of aphotodetector, and a distance measuring device (distance measuringinstrument).

BACKGROUND ART

There is a photodetector that uses an element that generates a signal inresponse to reception of a photon as a light receiving element (seePatent Document 1, for example). This type of photodetector adopts, as ameasurement method for measuring the distance to an object to bemeasured, a time of flight (ToF) method in which the time until lightemitted toward an object to be measured is reflected by the object to bemeasured and returns is measured.

CITATION LIST Patent Document Patent Document 1: Japanese PatentApplication Laid-Open No. 2016-211881 SUMMARY OF THE INVENTION Problemsto be Solved by the Invention

In a photodetector that uses, among the ToF methods, the direct ToFmethod in which the distance is measured directly from the flight timedifference of light, it is necessary to acquire light reception dataoutput from the light receiving element by a high-speed time measuringunit (time-to-digital converter: TDC). However, in a case where lightreception data output from one light receiving element is sampled inparallel with multiple clock phases, the peak power is large because thephotodetector operates at high speed during sampling. A large peak powerhas a great influence on the power supply design and the timing designwhen designing the photodetector.

Against this background, an object of the present disclosure is toprovide a photodetector capable of reducing peak power during a samplingoperation, a driving method of a photodetector, and a distance measuringdevice using the photodetector.

Solutions to Problems

A photodetector of the present disclosure for achieving the above objectincludes multiple pixels including a light receiving element, and asampling circuit that is provided corresponding to the multiple pixels,and samples light reception data output from the pixel on the basis ofmultiple clock signals having different phases, in synchronization withinput of a trigger signal.

The sampling circuit performs a sampling operation on the basis of aclock signal having a different phase every time a trigger signal isinput.

Additionally, a driving method of a photodetector of the presentdisclosure for achieving the above object includes the step of

when driving a photodetector that includes multiple pixels including alight receiving element, and a sampling circuit that is providedcorresponding to the multiple pixels, and samples light reception dataoutput from the pixel on the basis of multiple clock signals havingdifferent phases, in synchronization with input of a trigger signal,

performing a sampling operation in a sampling circuit on the basis of aclock signal having a different phase every time a trigger signal isinput.

Moreover, a distance measuring device (distance measuring instrument) ofthe present disclosure for achieving the above object includes

a light source that irradiates an object to be measured with light, and

a photodetector that detects light reflected by the object to bemeasured.

As the photodetector, a photodetector having the above configuration isused.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram showing a distance measuringdevice according to an embodiment of the present disclosure.

FIG. 2A and FIG. 2B are block diagrams showing a specific configurationof the distance measuring device.

FIG. 3 is a circuit diagram showing an example of the configuration of apixel circuit in a photodetector using a SPAD sensor.

FIG. 4 is a block diagram showing an example of a basic configuration ofthe photodetector according to the embodiment of the present disclosure.

FIG. 5 is an explanatory diagram of the basic operation of a samplingcircuit, where FIG. 5A shows the timing relationship among a slotsignal, a trigger signal, and the sampling timing, and FIG. 5B shows thetiming relationship between the trigger signal and two clock signals #0and #1.

FIG. 6 is a block diagram showing a circuit configuration of a signalprocessing circuit in a photodetector according to Example 1.

FIG. 7 is a block diagram for describing the circuit operation of afirst signal processing unit in the photodetector according to Example1.

FIG. 8 is a block diagram showing a circuit configuration of a signalprocessing circuit in a photodetector according to Example 2.

FIG. 9 is a block diagram for describing the circuit operation of afirst signal processing unit in the photodetector according to Example2.

FIG. 10 is a block diagram showing a circuit configuration of a signalprocessing circuit in a photodetector according to Example 3.

FIG. 11 is a block diagram for describing the circuit operation of afirst signal processing unit in the photodetector according to Example3.

FIG. 12 is a flowchart showing an example of processing of a drivingmethod of a photodetector according to Example 4.

FIG. 13 is a block diagram showing a schematic configuration example ofa vehicle control system which is an example of a mobile control systemto which the technology according to the present disclosure can beapplied.

FIG. 14 is a diagram showing an example of installation positions of animaging unit and an outside information detection unit in a mobilecontrol system.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a mode for carrying out the technology according to thepresent disclosure (hereinafter referred to as “embodiment”) will bedescribed in detail with reference to the drawings. The technologyaccording to the present disclosure is not limited to the embodiment. Inthe following description, the same elements or elements having the samefunction will be denoted by the same reference signs, and redundantdescription will be omitted. Note that the description will be given inthe following order.

1. General description of photodetector and distance measuring device ofpresent disclosure

2. Distance measuring device according to embodiment

2-1. Basic configuration of distance measuring device

2-2. Configuration example of pixel circuit using SPAD sensor

2-3. Basic configuration example of photodetector

3. Photodetector according to embodiment

3-1. Example 1 (Example in which circuit portions for two clock phasesare mounted as first signal processing unit)

3-2. Example 2 (Example in which circuit portion for only one clockphase is mounted as first signal processing unit)

3-3. Example 3 (Modification of Example 2: Example in which one circuitportion of first signal processing unit is divided according to clockphase, and clock phase is changed for each SPAD region)

3-4. Example 4 (Example of driving method of photodetector according toExample 4)

4. Application example of technology according to present disclosure(Example of mobile unit)

5. Conceivable configuration of present disclosure

<General Description of Photodetector and Distance Measuring Device ofPresent Disclosure>

In a photodetector and a distance measuring device of the presentdisclosure, the sampling circuit may have a latch circuit that performsa sampling operation of light reception data on the basis of a clocksignal having a different phase every time a trigger signal is input.

Moreover, in the photodetector and the distance measuring device of thepresent disclosure including the above-described preferableconfiguration, the sampling circuit may have multiple latch circuitsprovided corresponding to the phases of the multiple clock signals.Then, the multiple latch circuits may perform a sampling operation oflight reception data in turns, every time a trigger signal is input.

Alternatively, in the photodetector and the distance measuring device ofthe present disclosure including the above-described preferableconfiguration, the sampling circuit may have a single latch circuitcommonly provided for the phases of the multiple clock signals, and thesingle latch circuit may perform a sampling operation of light receptiondata in turns for each phase of the multiple clock signals.Additionally, the sampling circuit may have a selector circuit thatselects from the multiple clock signals for each phase and supplies theclock signal to the single latch circuit.

Alternatively, in the photodetector and the distance measuring device ofthe present disclosure including the above-described preferableconfiguration, the sampling circuit may have a single latch circuitcommonly provided for the phases of the multiple clock signals, and thesingle latch circuit may perform a sampling operation of light receptiondata in turns for each phase of the multiple clock signals by using thelight reception data of multiple pixels as a unit. Additionally, thesampling circuit may have a selector circuit that selects from themultiple clock signals for each phase and supplies the clock signal tothe single latch circuit by using the light reception data of multiplepixels as a unit.

Moreover, in the photodetector and the distance measuring device of thepresent disclosure including the above-mentioned preferableconfiguration, the light receiving element may include an element thatgenerates a signal in response to reception of a photon. Then, the lightreceiving element may include a single photon avalanche diode.

<Distance Measuring Device According to Embodiment>

First, the basic configuration of the distance measuring device to whichthe technology according to the present disclosure is applied (i.e.,distance measuring device according to implementation process of presentdisclosure) will be described with reference to FIG. 1.

[Basic Configuration of Distance Measuring Device]

FIG. 1 is a schematic configuration diagram showing the distancemeasuring device according to the embodiment of the present disclosure.A distance measuring device 1 according to the present embodimentadopts, as a measuring method for measuring the distance to a subject 10which is the object to be measured, a time of flight (ToF) method inwhich the time until light (e.g., laser beam having peak wavelength ininfrared wavelength region) emitted toward the subject 10 is reflectedby the subject 10 and returns is measured. In order to achieve distancemeasurement by the ToF method, the distance measuring device 1 accordingto the present embodiment includes a light source 20 and a photodetector30. Then, as the photodetector 30, a photodetector according to theembodiment of the present disclosure described later is used.

The basic configuration of the distance measuring device 1 is shown inFIGS. 2A and 2B. The light source 20 has, for example, a laser driver21, a laser light source 22, and a diffusing lens 23, and irradiates thesubject 10 with a laser beam. The laser driver 21 drives the laser lightsource 22 under the control of a control circuit 34 of the photodetector30. The laser light source 22 includes a semiconductor laser, forexample, and emits a laser beam when driven by the laser driver 21. Thediffusing lens 23 diffuses the laser beam emitted from the laser lightsource 22 and irradiates the subject 10 with the laser beam.

The photodetector 30 has a light receiving lens 31, an optical sensor 32which is a light receiving unit, a signal processing circuit 33, and thecontrol circuit 34. The photodetector 30 receives laser beam that isemitted by the laser irradiation unit 20 and returns after beingreflected by the subject 10. The light receiving lens 31 collects thereflected laser beam from the subject 10 on the light receiving surfaceof the optical sensor 32. The optical sensor 32 receives the reflectedlaser beam from the subject 10 that has passed through the lightreceiving lens 31 in pixel units and performs photoelectric conversion.Details of the optical sensor 32 will be described later.

The output signal of the optical sensor 32, that is, the light receptiondata output from the pixels is supplied to the signal processing circuit33. Under the control of the control circuit 34, the signal processingcircuit 33 measures a time t until the laser beam emitted from the lightsource 20 toward the subject 10 is reflected by the subject 10 andreturned to the photodetector 30, and outputs the time t as timeinformation detected by the photodetector 30. The distance to thesubject 10 can be obtained on the basis of the time information (time t)detected by the photodetector 30.

An example of a time measurement method is a method in which a timer isstarted at the emission timing of pulsed light from the light source 20and the timer is stopped at the reception timing of the pulsed light bythe photodetector 30, to measure the time t. An example of another timemeasurement method is a method in which pulsed light is emitted from thelight source 20 at a predetermined cycle, the cycle at which thephotodetector 30 receives the pulsed light is detected, and the time tis measured from the phase difference between the light emission cycleand the light reception cycle. The time measurement is performedmultiple times, and the time t can be measured by detecting the peak ofa histogram obtained by accumulating the times measured multiple times.

The control circuit 34 includes, for example, a central processing unit(CPU) or the like, and controls the light source 20 and the signalprocessing circuit 33 on the basis of a slot signal and a trigger signalgiven from the outside of the photodetector 30.

As the optical sensor 32, a two-dimensional array sensor (so-called areasensor) in which pixels including light receiving elements aretwo-dimensionally arranged in a matrix (array shape) can be used, or aone-dimensional array sensor (so-called line sensor) in which pixelsincluding light receiving elements are arranged in a linear shape can beused.

As the optical sensor 32, a sensor can be used in which the lightreceiving element of the pixel includes an element that generates asignal in response to reception of a photon, such as a single photonavalanche diode (SPAD) sensor. That is, in the photodetector 30according to this example, the light receiving element of the pixelincludes a SPAD sensor. Note that the light receiving element is notlimited to the SPAD sensor, and may be various elements such as anavalanche photo diode (APD) and a current assisted photonic demodulator(CAPD).

[Configuration Example of Pixel Circuit Using SPAD Sensor]

FIG. 3 shows an example of the configuration of a pixel circuit in thephotodetector 30 using the SPAD sensor. Here, the basic configurationfor one pixel is shown.

In the pixel circuit of a pixel 40 according to this example, thecathode electrode of a SPAD sensor 41 is connected to a terminal 42 towhich a power supply voltage V_(DD) is given, through a P-type MOStransistor Q_(L) which is a load, and the anode electrode of the SPADsensor 41 is connected to a terminal 43 to which an anode voltage V_(bd)is given. As the anode voltage V_(bd), a large negative voltage thatcauses avalanche multiplication is applied.

A capacitive element C is connected between the anode electrode and theground. Then, a cathode voltage V_(CA) of the SPAD sensor 41 is derivedas a SPAD output (pixel output) through a CMOS inverter 54 in which aP-type MOS transistor Q_(p) and an N-type MOS transistor Q_(n) areconnected in series.

A voltage equal to or higher than a breakdown voltage V_(BD) is appliedto the SPAD sensor 41. The excess voltage equal to or higher than thebreakdown voltage V_(BD) is called an excess bias voltage V_(EX), and isgenerally a voltage of about 2-5 V. The SPAD sensor 41 operates in aregion called Geiger mode where there is no DC stable point.

[Basic Configuration Example of Photodetector]

FIG. 4 shows an example of the basic configuration of the photodetector30. The photodetector 30 according to this configuration example uses,as the optical sensor 32, a two-dimensional array sensor in whichmultiple pixels 40 including a light receiving element (e.g., SPADsensor) are two-dimensionally arranged in a matrix (array). Each pieceof light reception data of the multiple pixels 40 is supplied to thesignal processing circuit 33.

The control circuit 34 controls the signal processing circuit 33 on thebasis of the slot signal and the trigger signal given from the outsideof the photodetector 30. The signal processing circuit 33 is providedcorresponding to multiple pixels 40, and is provided for each of themultiple pixels 40, for example. The signal processing circuit 33includes a first signal processing unit 51 in the first stage and asecond signal processing unit 52 in the latter stage, and, under thecontrol of the control circuit 34, performs signal processing fordistance measurement on each piece of light reception data output fromthe multiple pixels 40.

Specifically, the first signal processing unit 51 in the first stageuses the direct ToF method of calculating the distance directly from theflight time difference of light, to perform signal processing fordistance measurement on the basis of light reception data output fromthe pixel 40. That is, the first signal processing unit 51 is a timemeasurement circuit (TDC circuit) that measures the time t until lightemitted toward an object to be measured is reflected by the object to bemeasured and returns. The time measurement by the first signalprocessing unit 51 is performed multiple times, and the time t ismeasured by detecting the peak of the histogram obtained by accumulatingthe times measured multiple times.

The second signal processing unit 52 in the latter stage has a memory(e.g., SRAM), stores data for each pixel 40 output from the first signalprocessing unit 51, and outputs the data stored in the memory on thebasis of a clock signal common to all pixels.

The first signal processing unit 51 has, in its input stage, a samplingcircuit 60 that samples the light reception data output from the pixel40 on the basis of multiple clock signals having different phases.

Here, the operation of the sampling circuit 60 in a case where two clocksignals, a clock signal #0 having a phase of 0 degrees and a clocksignal #1 having a phase of 180 degrees, are used as multiple clocksignals having different phases will be described with reference toFIGS. 5A and 5B.

As shown in FIG. 5A, the slot signal input to the control circuit 34 isa signal that becomes active (e.g., high level) by regarding the sameSPAD region as one slot. The trigger signal is input to the controlcircuit 34 multiple times during the active period of the slot signal,that is, during one slot period.

Every time a trigger signal is input to the control circuit 34, thesampling circuit 60 samples light reception data output from the pixel40 in synchronization with the two clock signals #0 and #1 havingdifferent phases as shown in FIG. 5B. That is, the sampling circuit 60samples the light reception data output from the pixel 40 in parallelwith multiple clock phases. Then, the first signal processing unit 51stores the sampling data in the sampling circuit 60 for one slot period,and outputs the sampling data stored during the one slot period to thesecond signal processing unit 52 in the latter stage.

In a case where light reception data output from one SPAD sensor 41(pixel 40) is sampled in parallel with multiple clock phases asdescribed above, the TDC circuit (i.e., first signal processing unit 51)including the sampling circuit 60 of the clock signals #0 and #1operates at high speed during sampling. Hence, the IR drop is very largeand the peak power is large. A large peak power has a great influence onthe power supply design and the timing design when designing thephotodetector 30.

<Photodetector According to Embodiment>

In the present embodiment, in the sampling circuit 60 that is providedcorresponding to multiple pixels 40 and samples light reception dataoutput from the pixel 40 on the basis of multiple clock signals havingdifferent phases, every time a trigger signal is input, a samplingoperation is performed on the basis of a clock signal having a differentphase, in other words, a sampling operation is performed by switchingthe phase of the clock signal to be sampled.

By switching the phase of the clock signal to be sampled every time atrigger signal is input, in the sampling circuit 60, less circuitportions are activated during the sampling operation as compared to thecase where sampling is performed in parallel with multiple clock signalshaving different phases. Accordingly, the peak power during the samplingoperation can be reduced. Additionally, depending on the circuitconfiguration of the sampling circuit 60 (cases of Example 2 and Example3 described later), the circuit scale can be reduced as well.

Hereinafter, a specific example of the present embodiment for performinga sampling operation on the basis of a clock signal having a differentphase every time a trigger signal is input in the sampling circuit 60will be described.

Example 1

Example 1 is an example in which circuit portions for two clock phasesare mounted as a first signal processing unit 51. FIG. 6 shows a blockdiagram of the circuit configuration of a signal processing circuit 33in a photodetector 30 according to Example 1. Here, of the signalprocessing circuit 33 provided corresponding to each of the pixels 40,the circuit configuration of only one pixel is shown. This point is thesame for the examples described later.

The photodetector 30 according to Example 1 has, as the first signalprocessing unit 51, circuit portions 511 and 512 for two clock phases,and has, as a sampling circuit 60 in the input stage, a latch circuit 61for each of two clock signals #0 and #1 with different phases. The latchcircuit 61 includes two cascade-connected flip-flops 611 and 612, andtwo latch circuits 61 are arranged for the light reception data outputfrom one SPAD sensor 41 (pixel 40).

Then, one of the two latch circuits 61 samples and latches lightreception data on the basis of the clock signal #0, and supplies thelatched data to one circuit portion 511 of the first signal processingunit 51. The other of the two latch circuits 61 latches light receptiondata on the basis of the clock signal #1, and supplies the latched datato the other circuit portion 512 of the first signal processing unit 51.That is, one clock signal phase is sampled for one input of the triggersignal.

The circuit operation of the first signal processing unit 51 in thephotodetector 30 according to Example 1 of the above configuration willbe described with reference to FIG. 7.

In the sampling circuit 60, the two latch circuits 61 provided for eachof the two clock signals #0 and #1 having different phases perform asampling operation of light reception data in turns for each phase ofthe two clock signals #0 and #1, every time a trigger signal is input tothe control circuit 34. Specifically, every time a trigger signal isinput, one of the two latch circuits 61 latches the light reception dataon the basis of the clock signal #0 having a phase of 0 degrees, andthen the other of the two latch circuits 61 latches the light receptiondata on the basis of the clock signal #1 having a phase of 180 degrees.That is, at the input of the first trigger signal, the samplingoperation is performed only by the clock signal #0, and at the input ofthe next trigger signal, the sampling operation is performed only by theclock signal #1.

In FIG. 7, the left diagram shows the case where the sampling operationof light reception data is performed on the basis of the clock signal #0having a phase of 0 degrees, and the right diagram shows the case wherethe sampling operation of light reception data is performed on the basisof the clock signal #1 having a phase of 180 degrees.

As described above, in the first signal processing unit 51 of thephotodetector 30 according to Example 1, two latch circuits 61 providedfor each of two clock signals #0 and #1 having different phasesalternately (in turns) perform a sampling operation, every time atrigger signal is input. For this reason, during the sampling operation,in the first signal processing unit 51, one of the shaded circuitportions 512 and 511 does not operate, and only the other of the shadedcircuit portions 511 and 512 operates. That is, since the circuitportions activated during the sampling operation is halved compared tothe case where sampling is performed in parallel with the two clocksignals #0 and #1, the peak power during the sampling operation can bereduced to about ½.

Note that in Example 1, two clock signals, the clock signal #0 having aphase of 0 degrees and the clock signal #1 having a phase of 180degrees, are exemplified as multiple clock signals having differentphases. However, the invention is not limited to the two-phase clock,and may use a multi-phase clock having three or more phases. The largerthe number of phases, the greater the effect of reducing the peak powerduring the sampling operation. This point is the same for Example 2 andExample 3 described later.

Example 2

Example 2 is an example in which a circuit portion for only one clockphase is mounted as a first signal processing unit 51. FIG. 8 shows ablock diagram of the circuit configuration of a signal processingcircuit 33 in a photodetector 30 according to Example 2.

The photodetector 30 according to Example 2 has the first signalprocessing unit 51 including a circuit portion common to two clocksignals #0 and #1 having different phases, and has, as a samplingcircuit 60 in the input stage, a single latch circuit 61 commonlyprovided for the two clock signals #0 and #1. The latch circuit 61includes two cascade-connected flip-flops 611 and 612, and one latchcircuit 61 is arranged for the light reception data output from one SPADsensor 41 (pixel 40).

Then, in a stage preceding the clock input to the latch circuit 61, aselector circuit 62 is provided to select from the two clock signals #0and #1 for each phase and use the clock signal #0 or #1 as the clockinput of the single latch circuit 61. On the basis of a selection signalsynchronized with a trigger signal and supplied from the outside of thephotodetector 30, the selector circuit 62 selects the clock signal #0having a phase of 0 degrees when the selection signal is logic “1”, andselects the clock signal #0 having a phase of 180 degrees when theselection signal is logic “0”, for example.

The circuit operation of the first signal processing unit 51 in thephotodetector 30 according to Example 2 of the above configuration willbe described with reference to FIG. 9.

In the sampling circuit 60, the latch circuit 61 commonly provided forthe two clock signals #0 and #1 performs a sampling operation of lightreception data output from the pixel 40 in turns for each phase of theclock signal #0 or #1 selected by the selector circuit 62, every time atrigger signal is input.

In FIG. 9, the left diagram shows the case where the sampling operationof light reception data is performed on the basis of the clock signal #0having a phase of 0 degrees, and the right diagram shows the case wherethe sampling operation of light reception data is performed on the basisof the clock signal #1 having a phase of 180 degrees.

As described above, in the photodetector 30 according to Example 2,since the first signal processing unit 51 including the sampling circuit60 includes the circuit portion for one clock phase, in the case ofusing clock signals #0 and #1 of two phases, the circuit scale can bereduced by half. FIG. 8 illustrates the circuit configuration of thesignal processing circuit 33 corresponding to one pixel. However, sincethe signal processing circuit 33 is provided corresponding to each ofthe pixels 40, the circuit scale reduction effect of Example 2 is great.Moreover, in the first signal processing unit 51 including the samplingcircuit 60, less circuit portions are activated during the samplingoperation as compared to the case where sampling is performed inparallel with the two clock signals #0 and #1. Hence, the peak powerduring the sampling operation can be reduced to about ½.

Example 3

Example 3 is a modification of Example 2, and is an example in which onecircuit portion of a first signal processing unit 51 is dividedaccording to the clock phase, and the clock phase is changed for eachSPAD region. FIG. 10 shows a block diagram of the circuit configurationof a signal processing circuit 33 in a photodetector 30 according toExample 2.

In the photodetector 30 according to Example 3, one circuit portion ofthe first signal processing unit 51 in the case of Example 2 is dividedinto multiple circuit portions (two circuit portions 510 and 511 in thisexample) corresponding to two clock signals #0 and #1, and the circuitportions 510 and 511 are used appropriately for each SPAD region usingthe light reception data of multiple pixels 40 (i.e., multiple SPADsensors 41) as a unit.

Specifically, a selector circuit 62 selects from the two clock signals#0 and #1 for each phase on the basis of the selection signalsynchronized with a trigger signal, and uses the clock signal #0 or #1as the clock input of a single latch circuit 61 for each SPAD regionusing the light reception data of multiple pixels 40 as a unit. As aresult, one of the circuit portions 510 and 511 is used for a certainSPAD region, and the other of the circuit portions 510 and 511 is usedfor another SPAD region. Then, the sampling operation of light receptiondata is performed in turns for each phase of the two clock signals #0and #1 with the light reception data of multiple pixels 40 as a unit.

The circuit operation of the first signal processing unit 51 in thephotodetector 30 according to Example 3 of the above configuration willbe described with reference to FIG. 11.

In a sampling circuit 60, the latch circuit 61 commonly provided for thetwo clock signals #0 and #1 performs a sampling operation of lightreception data in turns for each phase of the clock signal #0 or #1selected by the selector circuit 62 in synchronization with the triggersignal, for each SPAD region using the light reception data of multiplepixels 40 as a unit.

In FIG. 11, the left diagram shows the case where a sampling operationis performed on the basis of the clock signal #0 on the circuit portion510 side, and a sampling operation is performed on the basis of theclock signal #1 on the circuit portion 511 side. Meanwhile, the rightdiagram shows the case where a sampling operation is performed on thebasis of the clock signal #1 on the circuit portion 510 side, and asampling operation is performed on the basis of the clock signal #0 onthe circuit portion 511 side.

As described above, in the photodetector 30 according to Example 3, thefirst signal processing unit 51 including the sampling circuit 60includes the circuit portion for one clock phase. Hence, as in Example2, in the case of using clock signals #0 and #1 of two phases, thecircuit scale can be reduced by half. Moreover, in the first signalprocessing unit 51 including the sampling circuit 60, less circuitportions are activated during the sampling operation as compared to thecase where sampling is performed in parallel with the two clock signals#0 and #1. Hence, the peak power during the sampling operation can bereduced to about ½ (=¼+¼).

Note that while the case where the first signal processing unit 51 isdivided into two upper and lower parts (#0 and #1) has been exemplified,the invention is not limited to the division into upper and lower parts.The first signal processing unit 51 may be divided into multiple upperand lower parts including four or more upper and lower parts (#0, #1,#0, and #1) using the light reception data of multiple pixels 40 as aunit.

Example 4

Example 4 is an example of the driving method of the photodetector 30according to the embodiment of the present disclosure. FIG. 12 shows aflowchart of an example of processing of the driving method of thephotodetector 30 according to Example 4.

The processing of the driving method of the photodetector 30 accordingto Example 4 is performed in the signal processing circuit 33 under thecontrol of the control circuit 34.

The control circuit 34 monitors input of the trigger signal (step S11),and if it determines that the trigger signal has been input (YES inS11), the control circuit 34 latches the light reception data on thebasis of the clock signal #0 having a phase of 0 degrees (step S12). Thecontrol circuit 34 then monitors input of the trigger signal again (stepS13).

If the control circuit 34 determines in the processing of step S13 thatthe trigger signal has been input (YES in S13), the control circuit 34latches the light reception data on the basis of the clock signal #1having a phase of 180 degrees (step S14). Thereafter, the controlcircuit 34 repeats the processing from step S11 to step S14 until thesampling operation ends.

As described above, in the driving method of the photodetector 30according to Example 4, every time a trigger signal is input, the twolatch circuits 61 provided for each of the two clock signals #0 and #1having different phases perform a sampling operation alternately (inturns). Consequently, the circuit portions activated during the samplingoperation is halved compared to the case where sampling is performed inparallel with the two clock signals #0 and #1. Hence, the peak powerduring the sampling operation can be reduced to about ½.

<Modification>

While the technology according to the present disclosure has beendescribed above on the basis of the preferred embodiment, the technologyaccording to the present disclosure is not limited to the embodiment.The configuration and structure of the photodetector and distancemeasuring device described in the above embodiment are examples, and canbe changed as appropriate. For example, in the above embodiment, thecase where the SPAD sensor is used as the light receiving element hasbeen described as an example. However, the light receiving element isnot limited to the SPAD sensor, and a similar action and effect can beobtained even in a case where an element such as APD or CAPD is used.

<Application Example of Technology According to Present Disclosure>

The technology according to this disclosure can be applied to variousproducts. A more specific application example will be described below.For example, the technology according to the present disclosure may beimplemented as a distance measuring device mounted on any type of mobileunit including a car, an electric car, a hybrid electric car, amotorcycle, a bicycle, a personal mobility, an airplane, a drone, aship, a robot, a construction machine, an agricultural machine(tractor), and the like.

[Mobile Unit]

FIG. 13 is a block diagram showing a schematic configuration example ofa vehicle control system 7000 which is an example of a mobile controlsystem to which the technology according to the present disclosure canbe applied. The vehicle control system 7000 includes multiple electroniccontrol units connected through a communication network 7010. In theexample shown in FIG. 13, the vehicle control system 7000 includes adrive system control unit 7100, a body system control unit 7200, abattery control unit 7300, an outside information detection unit 7400,an inside information detection unit 7500, and an integrated controlunit 7600. The communication network 7010 connecting the multiplecontrol units may be an on-vehicle communication network compliant withan arbitrary standard such as controller area network (CAN), localinterconnect network (LIN), local area network (LAN), and FlexRay(registered trademark), for example.

Each control unit includes a microcomputer that performs arithmeticprocessing according to various programs, a storage unit that stores aprogram executed by the microcomputer or parameters used for variousarithmetic operations, and a drive circuit that drives various devicesto be controlled. Each control unit includes a network I/F forcommunicating with other control units through the communication network7010, and a communication I/F for communicating with devices, sensors,or the like inside or outside the vehicle by wired communication orwireless communication. In FIG. 13, as the functional configuration ofthe integrated control unit 7600, a microcomputer 7610, ageneral-purpose communication I/F 7620, a dedicated communication I/F7630, a positioning unit 7640, a beacon receiving unit 7650, anin-vehicle device I/F 7660, an audio image output unit 7670, anin-vehicle network I/F 7680, and a storage unit 7690 are illustrated.The other control units similarly include a microcomputer, acommunication I/F, a storage unit, and the like.

The drive system control unit 7100 controls the operation of devicesrelated to the drive system of the vehicle according to variousprograms. For example, the drive system control unit 7100 functions as acontroller of a drive force generation device for generating a driveforce of a vehicle such as an internal combustion engine or a drivemotor, a drive force transmission mechanism for transmitting the driveforce to wheels, a steering mechanism that adjusts the steering angle ofthe vehicle, a braking device that generates a braking force of thevehicle, and the like. The drive system control unit 7100 may have afunction as a controller of an antilock brake system (ABS), anelectronic stability control (ESC), or the like.

A vehicle state detector 7110 is connected to the drive system controlunit 7100. The vehicle state detector 7110 includes, for example, atleast one of a gyro sensor that detects the angular velocity of theshaft rotational movement of the vehicle body, an acceleration sensorthat detects the acceleration of the vehicle, or a sensor for detectingan accelerator pedal operation amount, a brake pedal operation amount, asteering wheel steering angle, an engine speed, a wheel rotation speed,or the like. The drive system control unit 7100 performs arithmeticprocessing using a signal input from the vehicle state detector 7110 tocontrol an internal combustion engine, a drive motor, an electric powersteering device, a brake device, or the like.

The body system control unit 7200 controls the operation of variousdevices equipped on the vehicle body according to various programs. Forexample, the body system control unit 7200 functions as a controller ofa keyless entry system, a smart key system, a power window device, orvarious lamps such as a headlamp, a back lamp, a brake lamp, a blinker,or a fog lamp. In this case, the body system control unit 7200 mayreceive input of radio waves transmitted from a portable devicesubstituting for a key or signals of various switches. The body systemcontrol unit 7200 receives input of these radio waves or signals, andcontrols a door lock device, a power window device, a lamp, and the likeof the vehicle.

The battery control unit 7300 controls a secondary battery 7310 that isthe power supply source of the drive motor according to variousprograms. For example, the battery control unit 7300 receives input ofinformation such as the battery temperature, the battery output voltage,or the remaining capacity of the battery from a battery device includingthe secondary battery 7310. The battery control unit 7300 performsarithmetic processing using these signals to control the temperatureadjustment of the secondary battery 7310 or control a cooling device orthe like provided in the battery device.

The outside information detection unit 7400 detects information outsidethe vehicle equipped with the vehicle control system 7000. For example,at least one of an imaging unit 7410 or an outside information detector7420 is connected to the outside information detection unit 7400. Theimaging unit 7410 includes at least one of a time of flight (ToF)camera, a stereo camera, a monocular camera, an infrared camera, orother cameras. The outside information detector 7420 includes at leastone of an environment sensor for detecting the current weather, or anambient information detection sensor for detecting another vehicle, anobstacle, a pedestrian, or the like around the vehicle equipped with thevehicle control system 7000, for example.

The environment sensor may be at least one of a raindrop sensor thatdetects rainy weather, a fog sensor that detects fog, a sunshine sensorthat detects the degree of sunshine, or a snow sensor that detectssnowfall, for example. The ambient information detection sensor may beat least one of an ultrasonic sensor, a radar device, or a lightdetection and ranging or laser imaging detection and ranging (LIDAR)device. The imaging unit 7410 and the outside information detector 7420may be provided as independent sensors or devices, or may be provided asa device in which multiple sensors or devices are integrated.

Here, FIG. 14 shows an example of the installation positions of theimaging unit 7410 and the outside information detector 7420. Forexample, imaging units 7910, 7912, 7914, 7916, and 7918 are provided inat least one of positions of a front nose, a side mirror, a rear bumper,a back door, or an upper portion of a windshield in the vehicle interiorof a vehicle 7900. The imaging unit 7910 provided on the front nose andthe imaging unit 7918 provided on the upper portion of the windshield inthe vehicle interior mainly acquire images of the front of the vehicle7900. The imaging units 7912 and 7914 provided on the side mirrorsmainly acquire images of the sides of the vehicle 7900. The imaging unit7916 provided on the rear bumper or the back door mainly acquires animage of the rear of the vehicle 7900. The imaging unit 7918 provided onthe upper portion of the windshield in the vehicle interior is mainlyused to detect a preceding vehicle, or a pedestrian, an obstacle, atraffic light, a traffic sign, a lane, or the like.

Note that FIG. 14 shows an example of the imaging ranges of the imagingunits 7910, 7912, 7914, and 7916. An imaging range a indicates theimaging range of the imaging unit 7910 provided on the front nose,imaging ranges b and c indicate the imaging ranges of the imaging units7912 and 7914 provided on the side mirrors, respectively, and an imagingrange d indicates the imaging range of the imaging unit 7916 provided onthe rear bumper or the back door. For example, by superimposing thepieces of image data captured by the imaging units 7910, 7912, 7914, and7916, a bird's eye view image of the vehicle 7900 as viewed from abovecan be obtained.

Outside information detection parts 7920, 7922, 7924, 7926, 7928, and7930 provided on the front, rear, sides, corners, and the upper portionof the windshield in the vehicle interior of the vehicle 7900 may beultrasonic sensors or radar devices, for example. The outsideinformation detection parts 7920, 7926, and 7930 provided on the frontnose, the rear bumper, the back door, and the upper portion of thewindshield in the vehicle interior of the vehicle 7900 may be LIDARdevices, for example. These outside information detection parts 7920 to7930 are mainly used for detecting a preceding vehicle, a pedestrian, anobstacle, or the like.

Returning to FIG. 13, the description will be continued. The outsideinformation detection unit 7400 causes the imaging unit 7410 to capturean image of the outside of the vehicle, and receives the captured imagedata. Additionally, the outside information detection unit 7400 receivesdetection information from the outside information detector 7420connected thereto. In a case where the outside information detector 7420is an ultrasonic sensor, a radar device, or a LIDAR device, the outsideinformation detection unit 7400 causes transmission of ultrasonic waves,electromagnetic waves, or the like, and receives information on thereceived reflected waves. The outside information detection unit 7400may perform object detection processing or distance detection processingof a person, a vehicle, an obstacle, a sign, characters on a roadsurface, or the like on the basis of the received information. Theoutside information detection unit 7400 may perform environmentrecognition processing for recognizing rainfall, fog, road surfaceconditions, or the like on the basis of the received information. Theoutside information detection unit 7400 may calculate the distance tothe object outside the vehicle on the basis of the received information.

Additionally, the outside information detection unit 7400 may performimage recognition processing or distance detection processing ofrecognizing a person, a vehicle, an obstacle, a sign, characters on aroad surface, or the like on the basis of the received image data. Theoutside information detection unit 7400 may perform processing such asdistortion correction or position adjustment on the received image data,combine pieces of image data captured by different imaging units 7410,and generate a bird's eye view image or a panoramic image. The outsideinformation detection unit 7400 may perform viewpoint conversionprocessing using pieces of image data captured by different imagingunits 7410.

The inside information detection unit 7500 detects information insidethe vehicle. For example, a driver state detector 7510 that detects astate of a driver is connected to the inside information detection unit7500. The driver state detector 7510 may include a camera that imagesthe driver, a biometric sensor that detects biometric information of thedriver, a microphone that collects voice in the vehicle interior, andthe like. For example, the biometric sensor is provided on a seatsurface, a steering wheel, or the like, and detects biometricinformation of an occupant sitting in a seat or a driver who grips thesteering wheel. The inside information detection unit 7500 may calculatethe degree of fatigue or concentration of the driver or determinewhether or not the driver is asleep, on the basis of detectioninformation input from the driver state detector 7510. The insideinformation detection unit 7500 may perform processing such as noisecanceling processing on the collected audio signal.

The integrated control unit 7600 controls overall operations in thevehicle control system 7000 according to various programs. An input unit7800 is connected to the integrated control unit 7600. The input unit7800 is implemented by a device such as a touch panel, a button, amicrophone, a switch, or a lever on which an occupant can perform inputoperation, for example. The integrated control unit 7600 may receiveinput of data obtained by voice recognition of voice input by amicrophone. The input unit 7800 may be a remote control device usinginfrared rays or other radio waves, or an external connection devicesuch as a mobile phone or a personal digital assistant (PDA) compatiblewith the operation of the vehicle control system 7000, for example. Theinput unit 7800 may be a camera, for example, in which case the occupantcan input information by gesture. Alternatively, data obtained bydetecting the movement of a wearable device worn by the occupant may beinput. Moreover, the input unit 7800 may include an input controlcircuit or the like that generates an input signal on the basis ofinformation input by the occupant or the like using the above input unit7800, and outputs the input signal to the integrated control unit 7600,for example. By operating the input unit 7800, the occupant or the likeinputs various data or instructs the vehicle control system 7000 on aprocessing operation.

The storage unit 7690 may include a read only memory (ROM) that storesvarious programs executed by the microcomputer, and a random accessmemory (RAM) that stores various parameters, calculation results, sensorvalues, or the like. Additionally, the storage unit 7690 may beimplemented by a magnetic storage device such as a hard disc drive(HDD), a semiconductor storage device, an optical storage device, amagneto-optical storage device, or the like.

The general-purpose communication I/F 7620 is a general-purposecommunication I/F that mediates communication with various devicesexisting in an external environment 7750. The general-purposecommunication I/F 7620 may implement a cellular communication protocolsuch as global system of mobile communications (GSM) (registeredtrademark), WiMAX, long term evolution (LTE), or LTE-advanced (LTE-A),or another wireless communication protocol such as wireless LAN (alsoreferred to as Wi-Fi (registered trademark)) or Bluetooth (registeredtrademark). For example, the general-purpose communication I/F 7620 mayconnect to a device (e.g., application server or control server)existing in an external network (e.g., Internet, cloud network, ornetwork unique to business operator) through a base station or an accesspoint. Additionally, for example, the general-purpose communication I/F7620 may connect with a terminal (e.g., terminal of driver, pedestrian,or store, or machine type communication (MTC) terminal) existing in thevicinity of the vehicle by using the peer to peer (P2P) technology.

The dedicated communication I/F 7630 is a communication I/F thatsupports a communication protocol designed for use in a vehicle. Thededicated communication I/F 7630 may implement wireless access invehicle environment (WAVE), which is a combination of the lower layerIEEE802.11p and the upper layer IEEE1609, dedicated short rangecommunications (DSRC), or a standard protocol such as a cellularcommunication protocol, for example. The dedicated communication I/F7630 performs V2X communication, which is a concept that typicallyincludes one or more of vehicle to vehicle communication, vehicle toinfrastructure communication, vehicle to home communication, and vehicleto pedestrian communication.

For example, the positioning unit 7640 receives a global navigationsatellite system (GNSS) signal from a GNSS satellite (e.g., globalpositioning system (GPS) signal from GPS satellite) to performpositioning and generate position information including the latitude,longitude, and altitude of the vehicle. Note that the positioning unit7640 may identify the current position by exchanging signals with awireless access point, or may acquire position information from aterminal such as a mobile phone, a PHS, or a smartphone having apositioning function.

The beacon receiving unit 7650 receives radio waves or electromagneticwaves transmitted from a radio station or the like installed on theroad, and acquires information such as current location, trafficcongestion, traffic restrictions, or required time, for example. Notethat the function of the beacon receiving unit 7650 may be included inthe dedicated communication I/F 7630 described above.

The in-vehicle device I/F 7660 is a communication interface thatmediates connection between the microcomputer 7610 and variousin-vehicle devices 7760 existing in the vehicle. The in-vehicle deviceI/F 7660 may establish a wireless connection using a wireless LAN,Bluetooth (registered trademark), or a wireless communication protocolsuch as near field communication (NFC) or Wireless USB (WUSB).Additionally, the in-vehicle device I/F 7660 may establish a wiredconnection such as universal serial bus (USB), high-definitionmultimedia interface (HDMI) (registered trademark), mobilehigh-definition link (MHL), or the like through a connection terminal(and, if necessary, a cable) not shown. The in-vehicle device 7760 mayinclude at least one of a mobile device or a wearable device that anoccupant owns, or an information device that is carried in or attachedto the vehicle, for example. Additionally, the in-vehicle device 7760may include a navigation device that searches for a route to anarbitrary destination. The in-vehicle device I/F 7660 exchanges controlsignals or data signals with these in-vehicle devices 7760.

The in-vehicle network I/F 7680 is an interface that mediatescommunication between the microcomputer 7610 and the communicationnetwork 7010. The in-vehicle network I/F 7680 transmits and receivessignals and the like according to a predetermined protocol supported bythe communication network 7010.

The microcomputer 7610 of the integrated control unit 7600 controls thevehicle control system 7000 according to various programs, on the basisof information acquired through at least one of the general-purposecommunication I/F 7620, the dedicated communication I/F 7630, thepositioning unit 7640, the beacon receiving unit 7650, the in-vehicledevice I/F 7660, or the in-vehicle network I/F 7680. For example, themicrocomputer 7610 may calculate a control target value of the driveforce generation device, the steering mechanism, or the braking deviceon the basis of acquired information on the inside and outside of thevehicle, and output a control command to the drive system control unit7100. For example, the microcomputer 7610 may perform coordinatedcontrol aimed to achieve functions of an advanced driver assistancesystem (ADAS) including collision avoidance or shock mitigation of thevehicle, follow-up traveling based on an inter-vehicle distance, vehiclespeed maintenance traveling, vehicle collision warning, vehicle lanedeparture warning, or the like. Additionally, the microcomputer 7610 maycontrol the drive force generation device, the steering mechanism, thebraking device, or the like on the basis of acquired information on thesurroundings of the vehicle, to perform coordinated control aimed forautomatic driving of traveling autonomously without depending on thedriver's operation, for example.

The microcomputer 7610 may generate, on the basis of informationacquired through at least one of the general-purpose communication I/F7620, the dedicated communication I/F 7630, the positioning unit 7640,the beacon receiving unit 7650, the in-vehicle device I/F 7660, or thein-vehicle network I/F 7680, three-dimensional distance informationbetween the vehicle and objects such as surrounding structures andpersons, and create local map information including peripheralinformation of the current position of the vehicle. Additionally, themicrocomputer 7610 may predict a risk of a vehicle collision, proximityof a pedestrian or the like, or entry into a closed road, for example,on the basis of the acquired information, and generate a warning signal.The warning signal may be a signal for sounding a warning sound orlighting a warning lamp, for example.

The audio image output unit 7670 transmits an output signal of at leastone of audio or image to an output device capable of visually or aurallygiving notification of information to an occupant or to the outside ofthe vehicle. In the example of FIG. 13, an audio speaker 7710, a displayunit 7720, and an instrument panel 7730 are shown as examples of theoutput device. The display unit 7720 may include at least one of anonboard display or a head-up display, for example. The display unit 7720may have an augmented reality (AR) display function. The output devicemay be a device other than these devices, such as headphones, a wearabledevice such as an eyeglass-type display worn by an occupant, aprojector, or a lamp. In a case where the output device is a displaydevice, the display device visually displays results obtained by variousprocessing performed by the microcomputer 7610 or information receivedfrom another control unit in various formats such as text, images,tables, and graphs. Additionally, in a case where the output device is avoice output device, the voice output device converts an audio signalincluding reproduced voice data, acoustic data, or the like into ananalog signal and outputs the analog signal in an auditory manner.

Note that in the example shown in FIG. 13, at least two control unitsconnected through the communication network 7010 may be integrated asone control unit. Alternatively, each control unit may include multiplecontrol units. Moreover, the vehicle control system 7000 may includeanother control unit not shown. Additionally, in the above description,some or all of the functions of any control unit may be given to anothercontrol unit. That is, as long as information is transmitted andreceived through the communication network 7010, the predeterminedarithmetic processing may be performed by any control unit. Similarly, asensor or device connected to one of the control units may be connectedto another control unit, and multiple control units may transmit andreceive detection information to and from each other through thecommunication network 7010.

Hereinabove, an example of the vehicle control system to which thetechnology of the present disclosure can be applied has been described.Of the above-described configuration, the technology according to thepresent disclosure is applicable to a ToF camera in a case where theimaging unit 7410 includes the ToF camera, for example. Then, byapplying the technology according to the present disclosure, the peakpower during a sampling operation for distance measurement can bereduced, so that a vehicle control system with low power consumption canbe constructed, for example.

<Conceivable Configuration of Present Disclosure>

Note that the present technology can also be configured as follows.

<<A. Photodetector>>

[A-1] A photodetector including

multiple pixels including a light receiving element, and

a sampling circuit that is provided corresponding to the multiplepixels, and samples light reception data output from the pixel on thebasis of multiple clock signals having different phases, insynchronization with input of a trigger signal, in which

the sampling circuit performs a sampling operation on the basis of aclock signal having a different phase every time a trigger signal isinput.

[A-2] The photodetector according to [A-1] above, in which

the sampling circuit has a latch circuit that performs a samplingoperation of light reception data on the basis of a clock signal havinga different phase every time a trigger signal is input.

[A-3] The photodetector according to [A-2] above, in which

the sampling circuit has multiple latch circuits provided correspondingto the phases of the multiple clock signals, and

the multiple latch circuits perform a sampling operation of lightreception data in turns, every time a trigger signal is input.

[A-4] The photodetector according to [A-2] above, in which

the sampling circuit has a single latch circuit commonly provided forthe phases of the multiple clock signals, and

the single latch circuit performs a sampling operation of lightreception data in turns for each phase of the multiple clock signals.

[A-5] The photodetector according to [A-4] above, in which

the sampling circuit has a selector circuit that selects from themultiple clock signals for each phase and supplies the clock signal tothe single latch circuit.

[A-6] The photodetector according to [A-2] above, in which

the sampling circuit has a single latch circuit commonly provided forthe phases of the multiple clock signals, and

the single latch circuit performs a sampling operation of lightreception data in turns for each phase of the multiple clock signals byusing the light reception data of multiple pixels as a unit.

[A-7] The photodetector according to [A-6] above, in which

the sampling circuit has a selector circuit that selects from themultiple clock signals for each phase and supplies the clock signal tothe single latch circuit by using the light reception data of multiplepixels as a unit.

[A-8] The photodetector according to any one of [A-1] above to [A-7]above, in which

the light receiving element includes an element that generates a signalin response to reception of a photon.

[A-9] The photodetector according to [A-8] above, in which

the light receiving element includes a single photon avalanche diode.

<<B. Distance Measuring Device>>

[B-1] A distance measuring device including

a light source that irradiates an object to be measured with light, and

a light receiving device that receives light reflected by the object tobe measured, in which

the light receiving device includes multiple pixels including a lightreceiving element, and a sampling circuit that samples light receptiondata output from the pixel on the basis of multiple clock signals havingdifferent phases, and

the sampling circuit performs a sampling operation on the basis of aclock signal having a different phase every time a trigger signal isinput.

[B-2] The distance measuring device according to [B-1] above, in which

the sampling circuit has a latch circuit that performs a samplingoperation of light reception data on the basis of a clock signal havinga different phase every time a trigger signal is input.

[B-3] The distance measuring device according to [B-2] above, in which

the sampling circuit has multiple latch circuits provided correspondingto the phases of the multiple clock signals, and

the multiple latch circuits perform a sampling operation of lightreception data in turns, every time a trigger signal is input.

[B-4] The distance measuring device according to [B-2] above, in which

the sampling circuit has a single latch circuit commonly provided forthe phases of the multiple clock signals, and

the single latch circuit performs a sampling operation of lightreception data in turns for each phase of the multiple clock signals.

[B-5] The distance measuring device according to [B-4] above, in which

the sampling circuit has a selector circuit that selects from themultiple clock signals for each phase and supplies the clock signal tothe single latch circuit.

[B-6] The distance measuring device according to [B-2] above, in which

the sampling circuit has a single latch circuit commonly provided forthe phases of the multiple clock signals, and

the single latch circuit performs a sampling operation of lightreception data in turns for each phase of the multiple clock signals byusing the light reception data of multiple pixels as a unit.

[B-7] The distance measuring device according to [B-6] above, in which

the sampling circuit has a selector circuit that selects from themultiple clock signals for each phase and supplies the clock signal tothe single latch circuit by using the light reception data of multiplepixels as a unit.

[B-8] The distance measuring device according to any one of [B-1] aboveto [B-7] above, in which

the light receiving element includes an element that generates a signalin response to reception of a photon.

[B-9] The distance measuring device according to [B-8] above, in which

the light receiving element includes a single photon avalanche diode.

REFERENCE SIGNS LIST

-   1 Distance measuring device-   10 Subject (object to be measured)-   20 Light source-   21 Laser driver-   22 Laser light source-   23 Diffusing lens-   30 Photodetector-   31 Light receiving lens-   32 Optical sensor-   33 Signal processing circuit-   34 Control circuit-   40 Pixel-   41 SPAD sensor-   51 First signal processing unit-   52 Second signal processing unit-   60 Sampling circuit-   61 Latch circuit-   62 Selector circuit-   611, 612 Flip-flop

1. A photodetector comprising a plurality of pixels including a lightreceiving element, and a sampling circuit that is provided correspondingto the plurality of pixels, and samples light reception data output fromthe pixel on a basis of a plurality of clock signals having differentphases, in synchronization with input of a trigger signal, wherein thesampling circuit performs a sampling operation on a basis of a clocksignal having a different phase every time a trigger signal is input. 2.The photodetector according to claim 1, wherein the sampling circuit hasa latch circuit that performs a sampling operation of light receptiondata on a basis of a clock signal having a different phase every time atrigger signal is input.
 3. The photodetector according to claim 2,wherein the sampling circuit has a plurality of latch circuits providedcorresponding to the phases of the plurality of clock signals, and theplurality of latch circuits performs a sampling operation of lightreception data in turns, every time a trigger signal is input.
 4. Thephotodetector according to claim 2, wherein the sampling circuit has asingle latch circuit commonly provided for the phases of the pluralityof clock signals, and the single latch circuit performs a samplingoperation of light reception data in turns for each phase of theplurality of clock signals.
 5. The photodetector according to claim 4,wherein the sampling circuit has a selector circuit that selects fromthe plurality of clock signals for each phase and supplies the clocksignal to the single latch circuit.
 6. The photodetector according toclaim 2, wherein the sampling circuit has a single latch circuitcommonly provided for the phases of the plurality of clock signals, andthe single latch circuit performs a sampling operation of lightreception data in turns for each phase of the plurality of clock signalsby using the light reception data of a plurality of pixels as a unit. 7.The photodetector according to claim 6, wherein the sampling circuit hasa selector circuit that selects from the plurality of clock signals foreach phase and supplies the clock signal to the single latch circuit byusing the light reception data of a plurality of pixels as a unit. 8.The photodetector according to claim 1, wherein the light receivingelement includes an element that generates a signal in response toreception of a photon.
 9. The photodetector according to claim 8,wherein the light receiving element includes a single photon avalanchediode.
 10. A driving method of a photodetector comprising the step ofwhen driving a photodetector that includes a plurality of pixelsincluding a light receiving element, and a sampling circuit that isprovided corresponding to the plurality of pixels, and samples lightreception data output from the pixel on a basis of a plurality of clocksignals having different phases, in synchronization with input of atrigger signal, performing a sampling operation in a sampling circuit ona basis of a clock signal having a different phase every time a triggersignal is input.
 11. A distance measuring device comprising a lightsource that irradiates an object to be measured with light, and a lightreceiving device that receives light reflected by the object to bemeasured, wherein the light receiving device includes a plurality ofpixels including a light receiving element, and a sampling circuit thatsamples light reception data output from the pixel on a basis of aplurality of clock signals having different phases, and in the samplingcircuit, a circuit portion that performs the sampling operation isdifferent for each phase of the plurality of clock signals.